Jawabanmu

2014-08-25T22:26:36+07:00
15a +7b-5c-11a-12b +13d = 15a-11a+7b-12b-5c+13d = 4a - 5b - 5c + 13d Ini kalo bener. Kalo salah maaf.
9 3 9
2014-08-25T22:30:28+07:00
15a + 7b - 5c -11a - 12b + 13d =4a-5b-5c+13d


6 3 6